Process of making alkali perborates.



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OTTO LIEBKNECHT, E FRANKFORT-ON-THE-MAIN, GERMANY, ASSIGNGR TO THE ROESSLER & HASSLACHEB. CHEMICAL COMPANY, OF NEW YORK, N. Y., A 001t- PORATION DFNEW YORK.

PROCESS OF MAKING ALKALI PERBORATES.

Ito Drawing.

' Perborates, of which the following is a specification.

This process relates to the art of making perborates .and it particularly relates to a process for the electrolytic production of alkali perborate by an electrolytic process.

In U. S. patent application, Serial No.

70,592, filed January 6, 1916, Ihave described the manufacture of alkali perborate consisting in a double decomposition of a solution of electrolytically produced alkali percarbonate with a solution of an alkali borate and particularly a rocess of making sodium perborate consistlng in electrolyzing a solution of analkali carbonate and a sodium borate.

According to my application mentioned above sodium perborate is produced easily, if the work is carried out in the presence of a solid salt, preferably in the presence of solid perborate of sodium.

It has been found during the manufacture of perborate of sodium by .the electrolysis of an alkali-carbonate solution containing an alkali borate, that the yield of perborate per unit tpuantity of current is considerably lowered y the reducing action at the cathode.

' The discovery has now been made that it is possible to lncrease the yield to a considerable extent without any disturbing action, by addin to the electrolyte chromic acidor such cl iromates, the base of which does not have a decomposing eflect on alkali erborate solutions, tor instance salts of alalis, alkaline earths, including magnesia and beryllium, aluminium, etc. Other substances are also suitable for instance other salts of alkaline earths, and generally anysubstances capable of producing on the cathode a precipitate lowering the reducing action. The aioresaid precipitate may be' rious reactions, causing for instance decom- Specification of Letters Patent.

Application filed May a1, 1916. Serial No. moose.

position of water and producing an insoluble oxid or hydroxid at the cathode; moreover, the products generated at the cathode may react with ingredients of the electrolyte causing a precipitate on the cathode, etc. If desired this precipitate may be made more effective by making it .finer and uniformly dense by the addition of protective colloids, such as "for instance, albumin, starch, gumarabic, etc.

The use of a diaphragm which is usual in such cases, led for many reasons to inconveniences; for instance the pressure of the bath was considerably increased, and the composition of the electrolyte modified by the separatin action of the diaphragm. In order to avoid this, it would be necessary to take special precautions which render the process more dificult. By applying the new process they are not necessary.

inasmuch as the substance capable of producing, a precipitate on the cathode mentioned in the claims,'-includes the salts, or mixtures oi the salts of the alkaline earths T refrain from further mentioning them specifically in the claims.

I claim l. The process of manufacturing alkaliperborate by electrolyzing a solution of an alkalicarbonate and of an alkaliborate, which comprises adding to the electrolyte a substance capable of producing a precipitate on the cathode.

2. The recess of manufacturing alkaliperborate hy electrolyzing a solution of an alkalicarbonate and of an alkaliborate, which comprises adding to the electrolyte a ,mixture of substances capable of producing a precipitate on the cathode.

3. The process of manufacturing alkaliperborate by electrolyzing a solution of an alkalicarbonate and of an alkaliborate,

which comprises addin to the electrolyte a substance containing 0' romium capable of producing a precipitate on the cathode.

4. The process of manufacturing alkaliperborate by electrolyzing a solution of an alkalicarbonate and of an alkaliborate, which comprises adding'chromic acid to the electrolyte.

5. The process of manufacturing alkaliperborate by electrolyzing a solution of an alkalicarbonate and of an alkaliborate, h ch omprises adding to the electrolyte a Mitt chromate of a. base unable to decompose an alkaliperborate. I

6. The Process of manufacturing alkaliperborate by electrolyzing a solution of an alkalicarbonate and of an alkaliborate which comprises adding to the electrolyte a mixture of a chromate and of a salt of an alkaline earth capable of ci itate on the cathode.

The process of manufacturing alkali perborate by electrolyzing a solution of an alkalicarbonate and of an alkaliborate, which comprises adding to the electrolyte a protective colloid and a substance capable of producing a precipitate on the cathode.

8. The process of manufacturing sodiumproducing a preperborate by electrolyzing a solution of soda and borax, which comprises adding to the electrolyte a substance capable of producing a precipitate on the cathode.

9. The process of manufacturing sodiumperborate by electrolyzing a solution of soda and borax, which comprises addin to the electrolyte a protective colloid an a substance capable of producing a precipitate on the cathode.

In testimony'whereof I have signed my name to this specification in the presence of two subscribing witnesses.

OTTO LIEBKNECHT, Witnesses:

JEAN GRUND, HARRY EDWIN CARLsON. 

